The present invention is directed to a power striker for the latch of a sliding door, such as those employed on van type vehicles.
Most present day vans are provided with a sliding door which provides access to that portion of the interior of the van from one side of the van. When closed, the sliding door is seated within its door opening and a seal which extends around the periphery of the door opening is tightly compressed between a peripheral flange on the door and the vehicle body. The door is supported for movement upon the vehicle body by horizontal tracks which are curved inwardly toward the vehicle centerline near their front end. When the door is opened, this curve or inclined track section initially guides the door along an outwardly and rearwardly inclined path until the inner side of the door has been moved outwardly of the vehicle centerline a sufficient distance to clear the outer side of the vehicle so that the door may then be moved rearwardly parallel to the vehicle centerline to clear the door opening.
The conventional latching arrangement employed to latch these doors in their closed position typically employs a striker pin fixedly mounted upon the door frame at the rear edge of the door opening and a latch assembly mounted on the rear edge of the door which will interlock with the striker pin upon closure of the door. The latch assembly usually employs a pivoted latch member spring biased to an open position and so arranged that when it initially engages the stationary striker pin prior to the complete closing of the door, the final movement of the door to its fully closed position pivots the latch member into interlocking relationship with the striker. A spring biassed pawl then seats in a notch in the pivoting latch member to hold it in its interlocked position. Actuation of the door handle will disengage the pawl to release the latch.
It is well known that closing and latching such sliding doors requires a substantial amount of force. If sufficient force is not applied, the door will not latch in its closed position. There are two reasons why this is so. First, the door seal which extends continuously around the periphery of the opening must be tightly compressed when the door is closed in order to perform its intended function. Thus, the seal exerts a progressively increasing resistance to closing movement of the door as the door approaches its fully closed position. Second, the inter engagement between the latch and striker pin must positively hold the door in its fully closed position, thus it is normally necessary for the door to move at least slightly beyond its fully closed position before the latch member can shift into fully interlocked relationship with the stationary striker pin.
The closure problem set forth above is of special concern where a power drive arrangement for opening and closing the door is employed. When the door is closed manually, the person closing the door is in a position to check to see if the door is in fact firmly latched. Power operated closures typically have their greatest convenience when the door can be opened and closed by a switch or control located adjacent the drivers seat, and from this location it is not possible to manually confirm the door is fully latched.
In that the basic root of the closure problem is the stationary striker pin which requires that the door be at least in its fully closed position before the latch can be engaged, the possibility of employing a movable striker arrangement, such as those employed in automatic trunk closing mechanisms is suggested. In the automatic trunk closing mechanism, the striker is power driven to an elevated ready position when the trunk lid is open. Upon closure of the trunk lid, the latch mechanism is first interlocked or latched to the striker while the striker is in its elevated ready position. An electric motor is then energized to drive a nut and lead screw coupling to draw the striker and latched trunk lid downwardly until the lid is in its fully closed position.
While a movable striker driven by a power driven screw is well adapted for a trunk lid closure, there are several reasons why this arrangement is not practical for use as a sliding door closure.
These reasons include the fact that a substantial portion of the power applied to a screw drive is needed to overcome the frictional resistance inherent in the system. Also the placement of the switch which activates the drive is critical in that the drive begins to move at full speed immediately. The screw drive experts a constant power throughout its full range of movement and backloads the drive motor at the end range of movement.
The drive of the present invention has substantially less friction to overcome, driver at a sinusoidable variable velocity and power, and does not backload the motor at its end limits of movement.